The present invention relates to a method of displaying regions of interest (ROI) of a picture, a method of cutting out a region from the picture and an apparatus for carrying out these methods.
According to a typical one of the methods known heretofore for establishing a region of interest on a picture, a region designating device such as a mouse or the like is employed for marking the region of interest on the picture. In the case where there are present a plurality of regions of interest on a picture, the ordinal numbers indicating the sequence in which the regions of interest are designated are displayed in the vicinity of the regions of interest in one-to-one correspondence for the purpose of distinctively specifying the regions of interest. In FIG. 1 of the accompanying drawings, there are shown two regions of interest on a medical picture. Referring to the figure, when a region 2A indicated by a broken line is designated in a picture 2 generated on a display screen 1, the ordinal number "1" indicating its turn in the sequence of designation is displayed in the vicinity of the region 2A. Subsequent designation of a region 2B indicated also by a broken line in FIG. 1 is accompanied with the display of the ordinal number "2" in the vicinity of the region 2B.
According to a second one of the methods known heretofore, a region of interest is prepared independently of a picture, wherein a region of the picture which coincides with the region of interest is cut out. More particularly, referring to FIG. 2A of the accompanying drawings, a region of interest on a picture is first designated by means of an indicating device such as a mouse or the like while viewing the picture, whereby the region of interest is prepared as a figure or contour such as a line diagram 3A (hereinafter referred to as the mouse-drawn contour or diagram or figure or the like). Next, a circumscribing line 3B is generated for the mouse-drawn contour 3A. This can be accomplished by a computer.
In the generation of the circumscribing line 3B, a circle of a radius r having the center at a point 3b located near the mouse-drawn contour 3A is designated. When at least a point 3a on the mouse-drawn contour 3A exists within the circle, then the point 3b is regarded as a point which constitutes a part of the circumscribing line 3B. Next, after moving to a point disposed a predetermined distance from the point 3b in the direction indicated by an arrow in FIG. 2B, a similar procedure is repeated. In this manner, the circumscribing line 3B for the mouse-drawn contour 3A is generated. Parenthetically, the circle of the radius r may be represented by a matrix of 3.times.3 pixels, for example, in the case of a digital picture.
By making use of the mouse-drawn contour diagram 3A and the circumscribing line diagram 3B, a region of interest is cut out from the real picture.
The first mentioned prior art method is certainly advantageous whereby the operator that can easily specify the region of interest by virtue of the ordinal numbers affixed to the regions. However, a disadvantage of this prior art method can be seen in that portions of the picture located closely to the affixed numbers are difficult to view.
The second mentioned prior art method is notable in that memories for storing the line diagrams (i.e. the mouse-drawn contour diagram and the circumscribing line diagram) are prepared separately for cutting out a region from a picture. This method however suffers in that the procedure for preparing the circumscribing line diagram is required and that not only the circumscribing line diagram but also the mouse-drawn contour diagram has to be used for cutting out the region of interest from the picture. Besides, in the case of the second mentioned method, it is required to identify discriminatively the portions located inside and outside of the mouse-drawn contour, the procedure for which however is extremely complicated to its disadvantage.